Translation Unit for Wireless Power Transfer

ABSTRACT

In an embodiment, a wireless power transmitter module includes a sensing grid configured to detect a receiver, a movable wireless power transmitter unit including a wireless power transmitter coil, and a two-dimensional linear motor including a plurality of linear motor coils configured to move the movable wireless power transmitter unit in a two-dimensional plane towards a location of the receiver.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/837,332, filed on Apr. 1, 2020, which claims the benefit of U.S.Provisional Application No. 62/827,658, filed on Apr. 1, 2019, whichapplication is hereby incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to an electronic system andmethod, and, in particular embodiments, to wireless power transfer.

BACKGROUND

Wireless charging systems are becoming ubiquitous in today's society.For example, many smartphones and wearables implement wireless chargingtechnology. Ease of use, greater reliability, spatial freedom, reducedconnectors and openings, and the possibility of hermetically sealing areamong the benefits offered by wireless charging. Wireless chargingstandards allow for interoperability between different devices andmanufacturers. Some wireless charging standards, such as the Qi standardfrom the Wireless Power Consortium, are becoming widely adopted.

FIG. 1 shows exemplary wireless charging system 100. Wireless chargingsystem 100 includes a transmitter (TX) device 102 that includes atransmitter coil L_(TX), and a receiver (RX) device 104 that includes areceiver coil L_(RX). The efficiency of the wireless power transmissiongenerally depends on the coupling between the coil L_(TX) and coilL_(RX). The coupling between the coil L_(TX) and coil is generally basedon the relative position between the coil L_(TX) and coil L_(RX).

Wireless power applications generally require freedom of positioning ofthe RX device to allow ease of use and increase market adoption. Asingle, non-movable transmitter coil L_(TX) generally requires preciseplacement of the RX device. Multiple, overlapped transmitter coilsL_(TX) allow more freedom of positioning but increase cost, reducesystem efficiency and create more heat. Moving transmitter coils L_(TX)using servomechanisms driven with rotating servomotors have complexmechanisms that are expensive and prone to failure.

SUMMARY

In accordance with an embodiment, a wireless power transmitter moduleincludes a sensing grid configured to detect a receiver, a movablewireless power transmitter unit including a wireless power transmittercoil, and a two-dimensional linear motor including a plurality of linearmotor coils configured to move the movable wireless power transmitterunit in a two-dimensional plane towards a location of the receiver.

In accordance with an embodiment, a method for wireless power transferincludes detecting a receiver using a sensing grid, and moving a movablewireless power transmitter unit that includes a wireless powertransmitter coil in a two-dimensional plane towards a location of thereceiver using a two-dimensional linear motor.

In accordance with an embodiment, a wireless power transmitter moduleincludes a sensing grid having a sensing layer and configured to detecta receiver, a fixed layer that is parallel to the sensing layer andincludes a metal, a movable wireless power transmitter unit including awireless power transmitter coil, and a two-dimensional linear motor. Themovable wireless power transmitter unit is located between the sensinglayer and the fixed layer. The two-dimensional linear motor isconfigured to move the movable wireless power transmitter unit in atwo-dimensional plane towards a location of the receiver, where thetwo-dimensional plane is parallel to the sensing layer.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 shows an exemplary wireless charging system;

FIGS. 2A-2C show cross-section, perspective, and top view, respectively,of a transmitter module, according to an embodiment of the presentinvention;

FIG. 3 shows a movable wireless power transmitter unit of thetransmitter module of FIGS. 2A-2C, according to an embodiment of thepresent invention;

FIGS. 4 and 5 show TX coil of the movable wireless power transmitterunit of FIG. 3, according to an embodiment of the present invention;

FIGS. 6-8 show possible arrangements of linear motor coils inside thelinear motor coil layer of the movable wireless power transmitter ofFIG. 3, according to an embodiment of the present invention;

FIG. 9 shows a cross-section view of a transmitter module, according toan embodiment of the present invention;

FIG. 10 shows a sensing grid, according to an embodiment of the presentinvention;

FIGS. 11 and 12 show transmitter modules, according to embodiments ofthe present invention;

FIG. 13A shows a transmitter module, according to an embodiment of thepresent invention;

FIG. 13B shows a magnetic layer of the transmitter module of FIG. 13A,according to an embodiment of the present invention;

FIG. 14A shows a transmitter module, according to an embodiment of thepresent invention;

FIG. 14B shows the linear motor coil layer of FIG. 14A, according to anembodiment of the present invention;

FIG. 15A shows a transmitter module, according to an embodiment of thepresent invention; and

FIG. 15B shows a top view of the magnetic layer of FIG. 15A, accordingto an embodiment of the present invention.

Corresponding numerals and symbols in different figures generally referto corresponding parts unless otherwise indicated. The figures are drawnto clearly illustrate the relevant aspects of the preferred embodimentsand are not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the embodiments disclosed are discussed indetail below. It should be appreciated, however, that the presentinvention provides many applicable inventive concepts that can beembodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

The description below illustrates the various specific details toprovide an in-depth understanding of several example embodimentsaccording to the description. The embodiments may be obtained withoutone or more of the specific details, or with other methods, components,materials and the like. In other cases, known structures, materials oroperations are not shown or described in detail so as not to obscure thedifferent aspects of the embodiments. References to “an embodiment” inthis description indicate that a particular configuration, structure orfeature described in relation to the embodiment is included in at leastone embodiment. Consequently, phrases such as “in one embodiment” thatmay appear at different points of the present description do notnecessarily refer exactly to the same embodiment. Furthermore, specificformations, structures or features may be combined in any appropriatemanner in one or more embodiments.

Embodiments of the present invention will be described in a specificcontext, a wireless power system that includes a translation transmitterunit for wireless power transfer that operates, e.g., according to theQi standard. Embodiments of the present invention may operate withoutcomplying with the Qi standard. Applications of some embodiments,include consumer electronics (e.g., smartphones, tablets), wearables(e.g., smart watches) and automotive (e.g., infotainment systems), aswell as commercial and residential uses (e.g., sub-surface charging).Other applications are also possible.

In an embodiment of the present invention, a movable wireless powertransmitter unit moves in a two-dimensional (2D) plane towards awireless power receiver using a 2D linear motor. In some embodiments, asensing grid is used to detect the presence and location of thereceiver. In some embodiments, the sensing grid is also used to detectthe location of the movable wireless power transmitter unit.

FIGS. 2A-2C show cross-section, perspective, and top view, respectively,of a transmitter module 202, according to an embodiment of the presentinvention. Transmitter module 202 includes (e.g., encloses) movablewireless power transmitter unit 204. Movable wireless power transmitterunit 204 includes a transmitter coil L_(TX) of a TX device, such as TXdevice 102. In some embodiments, the entire TX device is implemented inmovable wireless power transmitter unit 204. In other embodiments, onlya portion of the TX device is implemented in movable wireless powertransmitter unit 204.

During normal operation, a receiver device, such as receiver device 104,may be placed over transmitter module 202 for wireless powertransmission. In some embodiments, receiver device 104 may be placed indirect contract with surface 202 a of transmitter module 202. In otherembodiments, such as in sub-surface wireless charging, receiver device104 may be placed over surface 202 a at a distance from surface 202 a(in the z-axis) greater than 0 cm, such as at 2 cm, 10 cm, or more. Insome embodiments, receiver device 104 may be placed at any (x,y)location in the surface 202 a plane.

Transmitter module 202 detects the presence and (x,y) location ofreceiver device 104, using, e.g., foreign object detection (FOD)techniques, and moves or places movable wireless power transmitter unit204 below receiver coil L_(RX) of receiver device 104. Once thetransmitter coil L_(TX) of wireless power transmitter unit 204 is belowreceiver coil L_(RX), wireless power transmission begins, e.g.,according to the Qi standard.

In some embodiments, a controller (not shown in FIGS. 2A-2C)implemented, e.g., in movable wireless power transmitter unit 204 isused to detect the presence and location of receiver device 104 and tocontrol movement of movable wireless power transmitter unit 204 (e.g.,by injecting or causing current to be injected in one or more linearmotor coils). Such controller may be implemented as a general purposecontroller, or as a custom controller that uses, e.g., combinatoriallogic coupled to a memory. Other implementation of the controller mayalso be used.

In some embodiments, movable wireless power transmitter unit 204 ispowered using a flexible power cable (not shown in FIGS. 2A-2C). Someembodiments may power movable wireless power transmitter unit 204 usinga flexible printed circuit board (PCB), or another type of laminatedstructure.

Transmitter device 102 and receiver device 104 may be implemented in anyway known in the art, such as using inductive or resonant charging, forexample.

In some embodiments, a 2D linear motor (not shown in FIGS. 2A-2C) isused to move wireless power transmitter unit 204 across the 2D (x,y)plane (inside transmitter module 202). In some embodiments, the 2Dlinear motor may be implemented as a 2D synchronous linear motor. Inother embodiments, the 2D linear motor may be implemented as a 2Dasynchronous linear motor.

A linear motor may be understood as a rotary electric motor in which therotor and stator circular magnetic field components are laid out in astraight line. A 2D linear motor (also referred to as a planar motor)may be implemented, e.g., with two linear motors that are orthogonal(e.g., perpendicular) to each other so as to allow movement in a plane.The general operation of planar motors is well understood in the art,thereby rendering additional explanations superfluous.

FIG. 3 shows movable wireless power transmitter unit 300, according toan embodiment of the present invention. Movable wireless powertransmitter unit 204 may be implemented as movable wireless powertransmitter unit 300. Movable wireless power transmitter unit 300includes TX coil layer 302, ferrite layer 304, and linear motor coillayer 306.

TX coil layer 302 includes one or more TX coils L_(TX) used for wirelesspower transmission. The TX coils L_(TX) may be implemented using wirewindings, PCB traces or stamped wire, for example. FIG. 4 shows singleTX coil 402, according to an embodiment of the present invention. TXcoil layer 302 may include TX coil 402. Coils with other shapes andnumber of windings may also be used.

As another example, FIG. 5 shows TX coils 502 and 504, according to anembodiment of the present invention. TX coil layer 302 may include aplurality of TX coils, such as TX coils 502 and 504. Coils with othershapes and number of windings may also be used.

In some embodiments, TX coil 504 (small winding) can be used to chargesmaller RX devices, such as headphones or smartwatches; and TX coil 502(large winding) may be used to charge larger devices, such assmartphones or tablets. In another possible implementation, TX coil 504(small winding) may be used to charge, e.g., smartphones while TX coil502 (large winding) may be used to charge, e.g., laptops. In someembodiments, TX coil layer 302 may include three TX coils, which may beused to charge devices as small as smartwatches and as large as laptops.

In some embodiments, the plurality of TX coils of TX coil layer 302 maybe used one at a time. In other embodiments, two (or more) TX coils ofTX coil layer 302 may be used simultaneously. In some embodiments, theTX coils may be used one at a time or simultaneously based on the typeof receiver device 104 that is being powered.

In some embodiments, linear motor coil layer 306 includes a plurality oflinear motor coils. The linear motor coils may be implemented using wirewindings, PCB traces or stamped wire, for example. In some embodiments,the number of linear motor coils in linear motor coil layer 306 may be 3or more.

In some embodiments, a fixed (e.g., aluminum) plate is attached to,e.g., surface 202 b of transmitter module 202. The direction of movementof movable wireless power transmitter unit 300 may be determined bywhich coils in linear motor coil layer 306 are activated and by thesequence of current flow through the activated coils.

In some embodiments, the plurality of linear motor coils may beactivated (e.g., pulsed with an electrical current), e.g., sequentiallyand, e.g., in an asynchronous manner, to achieve 2D movement. Someembodiments may use square wave signals for activating the linear motorcoils (e.g., in a phase-shifter manner), where the speed of movement ofmovable wireless power transmitter unit 300 is based on the frequency ofthe square wave signals. In some embodiments, the square wave signalsmay be modulated using pulse-width modulation (PWM).

For example, FIG. 6 shows arrangement 600 of linear motor coils,according to an embodiment of the present invention. Linear motor coillayer 306 may include arrangement 600 of linear motor coils.

As shown in FIG. 6, arrangement 600 includes 8 coils 601-608 that arepartially overlapping in a square pattern. Each of the 8 coils 601-608has one or more turns and has a square shape. In some embodiments, theshape of the coils of arrangement 600 may be different (e.g., such ascircular shape).

The direction of movement in arrangement 600 may be determined based onthe sequence of activation of the 8 coils. For example, activating(e.g., pulsing) a coil of the arrangement 600 may cause eddy currents inthe aluminum plate (not shown) that is beneath arrangement 600 (in thez-axis) so that the magnetic field created by the eddy currents interactwith the variable magnetic field generated by the activated coil to pushit in a particular direction. For example:

a) a left to right motion (positive direction in the x-axis) may beachieved by: simultaneously activating coils 601, 608, and 607, thensimultaneously activating coils 602 and 606, and then simultaneouslyactivating coils 603, 604 and 606;

b) a right to left motion (negative direction in the x-axis) may beachieved by: simultaneously activating coils 603, 604 and 606, thensimultaneously activating coils 602 and 606, and then simultaneouslyactivating coils 601, 608, and 607;

c) an up motion (positive direction in the y-axis) may be achieved by:simultaneously activating coils 605, 606 and 607, then simultaneouslyactivating coils 604 and 608, and then simultaneously activating coils601, 602 and 603;

d) a down motion (negative direction in the y-axis) may be achieved by:simultaneously activating coils 601, 602 and 603 then simultaneouslyactivating coils 604 and 608, and then simultaneously activating coils605, 606 and 607;

e) a clockwise rotating motion may be achieved by sequentiallyactivating coils 601, 602, 603, 604, 605, 606, 607, and 608; and

f) a counter-clockwise rotating motion may be achieved by sequentiallyactivating coils 601, 608, 607, 606, 605, 604, 603 and 602.

The motions a) to f) with respect to arrangement 600 are only exemplaryand may be combined to achieve motions in other directions, such as adiagonal movement.

As exemplified by motions a) to f), movable wireless power transmitterunit 300 may move in 2D (x,y axis), as well as rotate.

It is understood that arrangement 600 is only exemplary, and that otherarrangements are also possible. For example, FIG. 7 shows arrangement700 of linear motor coils 701-705, according to an embodiment of thepresent invention. Linear motor coil layer 306 may include arrangement700 of linear motor coils 701-705.

As shown in FIG. 7, arrangement 700 includes 5 coils that are partiallyoverlapping in a star pattern. Each of the 5 coils has one or more turnsand has a square shape. In some embodiments, the shape of the coils ofarrangement 700 may be different (e.g., such as circular shape).

Example of activation patterns for arrangement 700 include:

a) a left to right motion (positive direction in the x-axis) may beachieved by sequentially activating coils 704, 705 and 702.

b) a right to left motion (negative direction in the x-axis) may beachieved by sequentially activating coils 702, 705 and 704;

c) an up motion (positive direction in the y-axis) may be achieved bysequentially activating coils 703, 705 and 701;

d) a down motion (negative direction in the y-axis) may be achieved bysequentially activating coils 701, 705 and 703;

e) a clockwise rotating motion may be achieved by sequentiallyactivating coils 701, 702, 703 and 704; and

f) a counter-clockwise rotating motion may be achieved by sequentiallyactivating coils 701, 704, 703 and 702.

The motions a) to f) with respect to arrangement 700 are only exemplaryand may be combined to achieve motions in other directions, such as adiagonal movement.

As yet another example, FIG. 8 shows arrangement 800 of linear motorcoils, according to an embodiment of the present invention. Linear motorcoil layer 306 may include arrangement 800 of linear motor coils. Linearmotor coil layer 306 may include arrangement 800 of linear motor coils.

As shown in FIG. 8, arrangement 800 includes 10 coils 801-810 that arepartially overlapping in a circular pattern. Each of the 10 coils801-810 has one or more turns and has a circular shape. In someembodiments, the shape of the coils 801-810 of arrangement 800 may bedifferent (e.g., such as square shape).

Activation patterns for arrangement 800 include simultaneouslyactivating a first group of 3 coils, and then simultaneously activatinga second group of 3 coils opposite to the first group. For example, fora left to right motion (positive direction in the x-axis), coils 808,809 and 810 are simultaneously activating, and then coils 803, 804, and805 are simultaneously activating. In a similar manner, other movementsin the x, y plane may be achieved. Rotation (clockwise orcounter-clockwise) may be achieved by sequentially activating the coils(clockwise or counter-clockwise).

In some embodiments (e.g., as shown in FIG. 3), ferrite layer 304 isdisposed between TX coil layer 302 and linear motor coil layer 306. Forexample, in some embodiments, ferrite layer 304 is attached to thebottom of TX coil layer 302, and may prevent magnetic flux from linearmotor coil layer 306 to couple to the TX coil(s) L_(TX) of TX coil layer302. In some embodiments, ferrite layer 304 guides the AC magnetic fieldfor wireless power transfer as well as the low frequency and DC fieldsfor the planar motor coils, which may coexist without interference.

FIG. 9 shows a cross-section view of a transmitter module 902, accordingto an embodiment of the present invention.

As shown in FIG. 9, transmitter module 902 includes metal layer 904(e.g., attached to bottom surface 902 b of transmitter module 902). Insome embodiments, metal layer 904 may be implemented as an aluminumplate. Other metals, such as copper, may also be used.

In some embodiments, the presence of aluminum metal layer 904 may causemovable wireless power transmitter unit 300 to levitate above layer 904when moving (e.g., towards receiver device 104), thereby reducingfriction while moving, thereby advantageously increasing efficiencyand/or reducing noise while moving, e.g., towards receiver device 104.

In some embodiments, the transmitter module (e.g., 202 or 902) detectsthe presence and location of receiver device 104 using a sensing grid,e.g., that is attached to the top surface (e.g., 202 a, 902 a) of thetransmitter module (e.g., 202, 902). For example, FIG. 10 shows sensinggrid 1002, according to an embodiment of the present invention.

As shown in FIG. 10, sensing grid 1002 includes a plurality of sensingcoils 1012 arranged in rows and columns. In this embodiment, seven rowsand seven columns equally spaced are shown. In some embodiments, adifferent numbers of rows and columns (e.g., six rows and five columns)may be used. In some embodiments, the spacing between each of theplurality of sensing coils 1012 may be different. In some embodiments,other arrangements may also be used.

During normal operation, each sensing coil 1012 is energized, e.g., byconducting current through them. After energizing sensing coils 1012, avoltage that is related (e.g., proportional) to the strength of themagnetic field flowing through the core area (magnetic axis) of thesensing coil 1012 is generated. By measuring, e.g., after energizing,the voltage across terminals of each of the sensing coils 1012 (e.g., ina known manner), it is possible to detect disturbances in the magneticfield caused by a foreign object, thereby enabling the detection of thepresence of a foreign object, such as receiver device 104. In someembodiments, the location of receiver device 104 corresponds to thelocation of the sensing coil(s) 1012 detecting a disturbance). In someembodiments, detecting the disturbance includes comparing the measured(e.g., peak) voltage across the terminals of a sensing coil 1012 with athreshold voltage that corresponds to a non-disturbed sensing coil 1012.Other implementations, such as based in resonance frequency, and changesin the inductance of the sensing coil 1012, may also be used.

In some embodiments, the sensing grid may be used to detect the positionof the movable wireless power transmitter unit (e.g., 204, 300), e.g.,based on the voltages across sensing coils 1012. In some embodiments, atransmitter coil L_(TX) located in the movable wireless powertransmitter unit is energized and sensing grid determines the locationof the movable wireless power transmitter unit (e.g., 204, 300) based onthe magnetic disturbance caused by the energizing of the transmittercoil L_(TX).

In some embodiments, sensing grid 1002 may be implemented, for example,in a PCB. For example, in a PCB, sensing coils 1012 may be implementedusing PCB traces. Other implementations are also possible.

Once the location of receiver device 104 is detected, the transmittermodule (e.g., 202, 902) may cause the movable wireless power transmitterunit (e.g., 204, 300) to move towards receiver device 104. In someembodiments, a controller of the transmitter module may be used todetect the location of receiver device 104, and to control (e.g., via aflex PCB) the movable wireless power transmitter unit.

FIG. 11 shows transmitter module 1102, according to an embodiment of thepresent invention. As shown in FIG. 11, sensing grid 1002 may beattached to top surface 1102 a of transmitter module 1102.

During normal operation, controller 1120 may, e.g., periodically,energize sensing grid 1002 to detect the presence of receiver device104. Once the location of the presence of receiver device 104 isdetermined (e.g., based on voltages of sensing coils 1012), controller1120 may activate linear motor coils (e.g., of arrangement 600, 700 or800) of linear motor coil layer 306 to cause movable wireless powertransmitter unit 300 to move towards the location of receiver device104.

In some embodiments (e.g., as shown in FIG. 11), controller 1120 maysense when receiver device 104 is moved, e.g., during wireless powertransfer, and may cause movable wireless power transmitter unit 300 to,e.g., slowly move to follow the location of receiver device 104, e.g.,without interrupting the wireless power transfer between transmitterdevice 102 and receiver device 104.

In some embodiments, controller 1120 may be implemented, e.g., on top oflayer 302. Other implementations are also possible.

In some embodiments, the position and velocity of movable wireless powertransmitter unit 300 can be sensed using one or more optical sensors(e.g., 1122 and 1124), such as low resolution cameras, attached tomovable wireless power transmitter unit 300 and facing up towards thesensing grid 1002 or down towards metal layer 904. A grid pattern (notshown) can be printed on the bottom surface of sensing grid 1002 or topsurface of metal layer 904 to aid with detecting the speed, position andmoving direction of movable wireless power transmitter unit 300 using,e.g., an optical flow image processing algorithm. In some embodiments,the grid pattern includes features placed at larger intervals to helpwith calculating the absolute position of movable wireless powertransmitter unit 300.

In some embodiments, the position and velocity of movable wireless powertransmitter unit 300 can be sensed using inertial sensor 1126. Inertialsensor may be implemented with an accelerometer and/or gyroscope, forexample. Some embodiments may implement inertial sensor 1126 togetherwith optical sensors 1122 and/or 1124. Other embodiments may implementinertial sensor without implementing optical sensors 1122 and 1124.Other embodiments may not implement inertial sensor 1126.

In some embodiments, a ferrous layer (e.g., an iron plate) is attachedto metal layer 904. For example, FIG. 12 shows transmitter module 1202,according to an embodiment of the present invention. Transmitter module1202 may be implemented in a similar manner as transmitter module 1102and may operate in a similar manner as transmitter module 1102.Transmitter module 1202, however, includes ferrous layer 1204.

In embodiments in which ferrous layer 1202 is implemented below analuminum layer 904, efficiency of the linear motor (e.g., using linearmotor coils in linear motor coil layer 306) may be advantageouslyincreased. Embodiments that include ferrous layer 1202 below aluminumlayer 904 may not cause movable wireless power transmitter unit 300 tolevitate while moving. In some embodiments, a DC current may be injectedinto one or more of the linear motor coils of linear motor coil layer306 to cause movable wireless power transmitter unit 300 to be attractedto ferrous layer 1202, thereby advantageously preventing movement, e.g.,once the movable wireless power transmitter unit 300 and receiver device104 are aligned.

FIG. 13A shows transmitter module 1302, according to an embodiment ofthe present invention. Transmitter module 1302 may be implemented in asimilar manner as transmitter module 1202 and may operate in a similarmanner as transmitter module 1202. Transmitter module 1302, however,includes magnetic layer 1304.

FIG. 13B shows a top view of magnetic layer 1304, according to anembodiment of the present invention. As shown, magnetic layer 1304 ismagnetized with alternating North and South poles oriented perpendicularto surface 1304 a in a checkerboard pattern. In some embodiments,discrete magnets may be used, which may be arranged in a similar manneras shown in FIG. 13B. In some embodiments, ferrous layer 1204 is used toincrease the strength of the magnetic field on the top side of magneticlayer 1304.

During normal operation, the linear motor coils of linear motor coillayer 306 are activated synchronously with the magnetic pattern ofmagnetic layer 1304 to cause movement. In some embodiments, the linearmotor coils of linear motor coil layer 306 are aligned with the magneticpattern of magnetic layer 1304. For example, when one linear motor coilof linear motor coil layer 306 is aligned to a magnetic pole of magneticlayer 1304, another linear motor coil of linear motor coil layer 306 maysit, e.g., exactly, between two poles of the magnetic pattern ofmagnetic layer 1304.

FIG. 14A shows transmitter module 1402, according to an embodiment ofthe present invention. Transmitter module 1402 may be implemented in asimilar manner as transmitter module 1202 and may operate in a similarmanner as transmitter module 1202. Transmitter module 1402, however,includes linear motor coil layer 1404 and movable wireless powertransmitter unit 1410 includes metal (e.g., aluminum) layer 1406.

During normal operation, controller 1420 causes movable wireless powertransmitter unit 1410 to move by activating linear motor coils of linearmotor coil layer 1404 in an asynchronous manner.

FIG. 14B shows linear motor coil layer 1404, according to an embodimentof the present invention. As shown in FIG. 14B, linear motor coil layer1404 includes a plurality of circular coils that are partiallyoverlapping in a square pattern. Each of the plurality of circular coilshas one or more turns. In some embodiments, the shape of the coils oflinear motor coil layer 1404 may be different (e.g., such as squareshape).

The direction of movement of movable wireless power transmitter unit1410 may be determined based on the sequence of activation of theplurality of linear motor coils of linear motor coil layer 1404, andbased on the location of movable wireless power transmitter unit 1410.For example, activating (e.g., pulsing) a linear motor coils of linearmotor coil layer 1404 (e.g., that is beneath movable wireless powertransmitter unit 1410 in the z-axis) may cause eddy currents in themetal (e.g., aluminum) plate 1406 so that the magnetic field created bythe eddy currents interact with the variable magnetic field generated bythe activated coil to push it in a particular direction. Activationpatterns, similar to the patterns discussed with respect to FIGS. 6-8may be used to cause movable wireless power transmitter unit 1410 tomove in a desired direction.

In some embodiments, controller 1420 may be implemented near an edge oftransmitter module 1402, for example.

As shown in FIG. 14A, transmitter module 1402 includes ferrous layer1204 below linear motor coil layer 1404. In some embodiments, ferrouslayer 1204 may be replaced with a ferrite layer.

FIG. 15A shows transmitter module 1502, according to an embodiment ofthe present invention. Transmitter module 1502 may be implemented in asimilar manner as transmitter module 1402 and may operate in a similarmanner as transmitter module 1402. Transmitter module 1502, however,includes movable wireless power transmitter unit 1510, which includesmagnetic layer 1504.

FIG. 15B shows a top view of magnetic layer 1504, according to anembodiment of the present invention. As shown, magnetic layer 1504 ismagnetized with alternating North and South poles in a checkerboardpattern. In some embodiments, discrete magnets may be used, which may bearranged in a similar manner as shown in FIG. 15B.

During normal operation, controller 1420 causes movable wireless powertransmitter unit 1410 to move by activating linear motor coils of linearmotor coil layer 1404 synchronously with the magnetic pattern ofmagnetic layer 1504 to cause movement of movable wireless powertransmitter unit 1510. In some embodiments, the linear motor coils oflinear motor coil layer 1404 are aligned with the magnetic pattern ofmagnetic layer 1504. For example, when one linear motor coil of linearmotor coil layer 1404 is aligned to a magnetic pole of magnetic layer1504, another linear motor coil of linear motor coil layer 1404 may sit,e.g., exactly, between two poles of the magnetic pattern of magneticlayer 1504.

Example embodiments of the present invention are summarized here. Otherembodiments can also be understood from the entirety of thespecification and the claims filed herein.

Example 1. A wireless power transmitter module including: a sensing gridconfigured to detect a receiver; a movable wireless power transmitterunit including a wireless power transmitter coil; and a two-dimensionallinear motor including a plurality of linear motor coils configured tomove the movable wireless power transmitter unit in a two-dimensionalplane towards a location of the receiver.

Example 2. The wireless power transmitter module of example 1, where themovable wireless power transmitter unit further includes an opticalsensor.

Example 3. The wireless power transmitter module of one of examples 1 or2, where the movable wireless power transmitter unit further includes aninertial sensor.

Example 4. The wireless power transmitter module of one of examples 1 to3, where the two-dimensional linear motor is a two-dimensionalasynchronous linear motor configured to move the movable wireless powertransmitter unit in any direction of the two-dimensional plane.

Example 5. The wireless power transmitter module of one of examples 1 to4, where the two-dimensional asynchronous linear motor includes aconductive plate, and where the plurality of linear motor coils areconfigured to be powered so that the movable wireless power transmitterunit moves in a direction parallel to the sensing grid based on a forcecreated between at least one of the plurality of linear motor coils andthe conductive plate.

Example 6. The wireless power transmitter module of one of examples 1 to5, where the movable wireless power transmitter unit includes theconductive plate.

Example 7. The wireless power transmitter module of one of examples 1 to6, where the conductive plate is an aluminum (Al) plate.

Example 8. The wireless power transmitter module of one of examples 1 to7, where the two-dimensional linear motor is a two-dimensionalsynchronous linear motor configured to move the movable wireless powertransmitter unit in any direction of the two-dimensional plane.

Example 9. The wireless power transmitter module of one of examples 1 to8, where the two-dimensional synchronous linear motor includes amagnetic layer, and where the plurality of linear motor coils areconfigured to be powered so that the movable wireless power transmitterunit moves in a direction parallel to the sensing grid based on a forcecreated between at least one of the plurality of linear motor coils andthe magnetic layer.

Example 10. The wireless power transmitter module of one of examples 1to 9, where the movable wireless power transmitter unit includes themagnetic layer.

Example 11. The wireless power transmitter module of one of examples 1to 10, where the magnetic layer includes discrete magnets.

Example 12. The wireless power transmitter module of one of examples 1to 11, where the movable wireless power transmitter unit includes: alinear motor coil layer that includes the plurality of linear motorcoils; and a ferrite layer located between the wireless powertransmitter coil and the linear motor coil layer.

Example 13. The wireless power transmitter module of one of examples 1to 12, where the movable wireless power transmitter unit includes: aconductive layer; and a ferrite layer located between the wireless powertransmitter coil and the conductive layer.

Example 14. The wireless power transmitter module of one of examples 1to 13, where the movable wireless power transmitter unit includes: amagnetic layer; and a ferrite layer located between the wireless powertransmitter coil and the magnetic layer.

Example 15. The wireless power transmitter module of one of examples 1to 14, further including a fixed conductive layer, where the movablewireless power transmitter unit is located between the sensing grid andthe fixed conductive layer.

Example 16. The wireless power transmitter module of one of examples 1to 15, further including a fixed ferrous layer, where the fixedconductive layer is located between the movable wireless powertransmitter unit and the fixed ferrous layer.

Example 17. The wireless power transmitter module of one of examples 1to 16, further including a fixed magnetic layer, where the movablewireless power transmitter unit is located between the sensing grid andthe fixed magnetic layer.

Example 18. The wireless power transmitter module of one of examples 1to 17, further including a fixed linear motor layer that includes theplurality of linear motor coils, where the movable wireless powertransmitter unit is located between the sensing grid and the fixedlinear motor layer.

Example 19. A method for wireless power transfer, the method including:detecting a receiver using a sensing grid; and moving a movable wirelesspower transmitter unit that includes a wireless power transmitter coilin a two-dimensional plane towards a location of the receiver using atwo-dimensional linear motor.

Example 20. A wireless power transmitter module including: a sensinggrid configured to detect a receiver, the sensing grid located in asensing layer; a fixed layer that is parallel to the sensing layer, thefixed layer including a metal; a movable wireless power transmitter unitincluding a wireless power transmitter coil, the movable wireless powertransmitter unit located between the sensing layer and the fixed layer;and a two-dimensional linear motor including a plurality of linear motorcoils configured to move the movable wireless power transmitter unit ina two-dimensional plane towards a location of the receiver, where thetwo-dimensional plane is parallel to the sensing layer.

Example 21. The wireless power transmitter module of example 20, furtherincluding a position sensor configured to determine a location of themovable wireless power transmitter unit using the sensing grid.

Example 22. The wireless power transmitter module of one of examples 20or 21, where the sensing layer includes an optical pattern, and wherethe position sensor includes an optical sensor directed towards theoptical pattern.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

What is claimed is:
 1. A wireless power transmitter comprising: asensing grid configured to detect a receiver; a movable wireless powertransmitter comprising a wireless power transmitter coil; and atwo-dimensional linear motor comprising a plurality of linear motorcoils configured to move the movable wireless power transmitter in atwo-dimensional plane towards a location of the receiver.